5 请问设备框架对接的问题？

发布于 2023-08-21 16:50:25 浏览：453 订阅该版

[tocm]

最近在看设备驱动的代码，以串口举例，我用了3个串口 ，uart1 uart3 uart6。所以uart_obj数组里是3个元素
`static struct stm32_uart uart_obj[sizeof(uart_config) / sizeof(uart_config[0])] = {0};`
此时uart_obj里都是 0，代码里也没找到给`uart_obj[1].serial`赋值的地方，此时`uart_obj[1].serial`应该也是0，那为什么可以这样呢。

```c
uart_obj[i].serial.ops    = &stm32_uart_ops;
uart_obj[i].serial.config = config;
```

```c
int rt_hw_usart_init(void)
{
    rt_size_t obj_num = sizeof(uart_obj) / sizeof(struct stm32_uart);
    struct serial_configure config = RT_SERIAL_CONFIG_DEFAULT;
    rt_err_t result = 0;

stm32_uart_get_dma_config();

for (int i = 0; i < obj_num; i++)
    {
        /* init UART object */
        uart_obj[i].config = &uart_config[i];
        uart_obj[i].serial.ops    = &stm32_uart_ops;
        uart_obj[i].serial.config = config;

/* register UART device */
        result = rt_hw_serial_register(&uart_obj[i].serial, uart_obj[i].config->name,
                                       RT_DEVICE_FLAG_RDWR
                                       | RT_DEVICE_FLAG_INT_RX
                                       | RT_DEVICE_FLAG_INT_TX
                                       | uart_obj[i].uart_dma_flag
                                       , NULL);
        RT_ASSERT(result == RT_EOK);
    }

return result;
}
```

## 问题二：
在`rt_hw_serial_register`函数里有代码如下：

```c
device->init        = rt_serial_init;
device->open        = rt_serial_open;
device->close       = rt_serial_close;
device->read        = rt_serial_read;
device->write       = rt_serial_write;
device->control     = rt_serial_control;
```
这样一来，三个串口每个都有这样的操作函数

然后`#define		ENV_NAME	"uart3"`
`env_dev = rt_device_find(ENV_NAME);`   执行这条语句之前，env_dev是0；执行之后env_dev就有了和uart_obj[1]相同的地址。
没搞明白IO设备管理和设备驱动框架层，也就是device 和serial是怎么联系起来的，
比如`rt_device_control(env_dev, RT_DEVICE_CTRL_CONFIG, &pconfig);`是怎么调用到

```c
static rt_err_t rt_serial_control(struct rt_device *dev,
                                  int              cmd,
                                  void             *args)
```
的呢。

我看到`rt_hw_serial_register`函数里调用`ret = rt_device_register(device, name, flag); `
再调用`rt_object_init(&(dev->parent), RT_Object_Class_Device, name);`

`rt_device_find` 函数里有 `return (rt_device_t)rt_object_find(name, RT_Object_Class_Device);`
但是没看明白。